The San Jose pluton is a 117 sq km syntectonic body of chemically homogeneous biotite-hornblende tonalite in the western part of the Cretaceous Peninsular Range batholith. Contacts with lower Cretaceous volcanic and volcaniclastic wall rocks define a teardrop outline, elongate north-south. The outline of the northern 2/3 is remarkably circular and concordant to isoclinally folded, highly stretched strata. Southward the contact becomes discordant and tapers irregularly to a point. Detailed mapping revealed three texturally distinguishable lithologies emplaced in two or possibly three intrusive pulses: (1) prismatic hornblende tonalite (PHbT) partially enclosed by (2) a horseshoe-shaped shell of stubby hornblende tonalite comprise the northern 2/3 of the pluton; (3) seriate porphyritic tonalite structurally and petrographically gradiational into the PHbT forms the discordant southern wedge.
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- Lower California (Mexico);
- Igneous Rocks;
- Structural Properties (Geology);